Biodiversity Hotspots (HL) (DP IB Environmental Systems & Societies (ESS))

Biodiversity Hotspots

What are biodiversity hotspots?

• Biodiversity hotspots are areas on Earth that contain a large number of different species, particularly those that are:

  • Rare

  • Endemic (found only in that area)

  • Endangered

• These regions are critical for conservation because they often have species that are not found anywhere else in the world

• Hotspots are regions of high biodiversity

  • However, they are also often the regions that are most under threat from human activities such as deforestation, pollution, and habitat destruction

Hotspot criteria

• To qualify as a biodiversity hotspot, an area must meet two main criteria:

  1. High endemism: the area must contain at least 1,500 species of vascular plants that are endemic

  2. Significant habitat loss: the area must have lost at least 70% of its original natural vegetation—this indicates that the region is under severe threat from human activities and is in urgent need of conservation

• These criteria, developed by ecologist Norman Myers and used by Conservation International, focus on areas of both high biodiversity and critical levels of habitat loss

• The Amazon rainforest does not currently qualify as a biodiversity hotspot because it has not yet met the second key criterion for being classified as one

  • Although it is facing significant deforestation and other threats, the Amazon has not yet reached the 70% threshold of habitat destruction, though deforestation rates are increasing

Uneven distribution of biodiversity

• Biodiversity is not evenly spread across the planet

  • Some areas, like the poles, have low biodiversity, while others, like tropical rainforests, have very high biodiversity

• Hotspots make up less than 3% of Earth's surface but contain more than half of the world’s plant species and a large percentage of its animal species

• Hotspots are often located in areas with unique climates and geographical features, which allow species to evolve and adapt to specific niches

Hotspots in tropical biomes

• Many hotspots are in tropical biomes

  • Tropical biomes tend to have the highest levels of biodiversity

  • The warm, wet conditions in tropical rainforests, for example, support a wide range of plants, insects, birds, and mammals

• Examples of tropical hotspots include:

  • The Coral Triangle in Southeast Asia, home to more than 600 species of reef-building corals

  • The Madagascar hotspot, where over 90% of the species are endemic

• Tropical biomes are mainly found in a band between 15° north and 15° south of the equator within the equatorial climate zone

• Covering only 6% of the Earth's surface, the main areas covered by tropical ecosystems are in the following countries:

  • Amazon: the largest remaining rainforest on Earth, usually associated with Brazil but covering parts of seven other countries in South America

  • Central America: including parts of Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama

  • Central Africa: including Cameroon, the Central African Republic, the Republic of Congo, the Democratic Republic of Congo (DRC), Equatorial Guinea and Gabon

  • Indo-Malaysia: including Malaysia, Indonesia and a number of other countries in South-East Asia